Fast impulse circuits



Jan. 2, 1951 w. A. HIGINBOTHAM 2,536,808

FAST IMPULSE CIRCUITS Filed March 8, 1949 4 Sheets-Sheet l Jan. 2, 1951 w, HIGINBOTHAM 2,536,808

FAST IMPULSE CIRCUITS Filed March 8, 1949 4 Sheets-Sheet 2 In ra? Jan. 2, 1951 w. A. HIGINBOTHAM 2,536,808

FAST IMPULSE CIRCUITS Filed March 8, 1949 4 Sheets-Sheet 5 Input? 13+ 13+ 106 Oui z 108 105 104 -Z I o 94; L 5-; 107

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INVENTOR. H/Z'llz'am A. Hz'gz'nbollzam 1951 w. A. HIGINBOTHAM 2,536,803

FAST IMPULSE CIRCUITS Filed March 8, 1949 4 Sheets-Sheet 4 Flip Flop IN VEN TOR.

ml/l'am A. Higl'nboifi am Patented Jan. 21, 1951 UNITED. STATES PATENT orslcsf to theUnited States of Americaas representedbyv the" United States Atomic Energy Commis-:

sion

ApplicationfMarch 8, 1949; Serial No. 801271 This application is a continuation-in-partoi application Serial Number 566,001,- filed November' 30, '1944. I

This invention" relates broadly to impulserdsponsivecircuits and more particularly, tc-circuits and apparatus-"adapted-to generate 'im pulses=at a fractional rate of theoccurrence of':

observed phenomena.

Circuits of this typearenecessary to enable the recording or indicating by mechanical instruments of the rate of occurrence of phenomena in the form ofshort-impulses occurring in rapid succession.

A representative ca'seaof such phenomena -is the generation ofparti'clesby radioactive andnuclear disintegration. The rate of occurrence of such particles mayextendinto the megacycle' per second range.

The apparatus organization for the measuring: ofthe rate of occurrence of observed phenomena comprises three major-processes. .7

The first process effects the translation of the observed physical phenomena into electrical im pulses. For example, the occurrence'ofparticles generated by radioactivity" 'are translated. into corresponding 1 electrical 1 impulses by means of the ionization chamber;

The secondmajor process in measuring-the rateof-occurrence of observed phenomena is the scaling downnof the .rate Of occurrence into a rate in the order of magnitude within thejscapabilities-of recording or indicating instruments.

The. third process comprises the'tra'nslationof electrical impulses generated at a rate within theorder. of capability .of v a mechanical instrument into an indication or recording The. present invention is confined to circuits and apparatus for the-accomplishment ofl theu translation of .fast'occurring electrical impulses" into. electrical impulses whichoccur at a fractionof'said rate A device'applied to the: pur-" pose is subject to rigorous requirements iwith respect to speed of=responseand accuracy. .The

rate of occurrence of electrical impulses impressed on the deviceimayirange from a few to a improved circuit fortranslatingthe rate of '00- megacycle ormoreper second The amount of scaling. downrequired may therefore befof extremely; high order. It follows-that if eachstage of the device is inherently capable of scaling down by. a factor of .tWo, a large scaling'factor requires the inter-coupling :of :a large number'of stages.

A singlespurious impulse generated 'by' theilast. stage of n cascaded stages, results in an error *ofZ in the count of the phenomena being observed;

A numberof types of scaling down circuits are known inthe prior art.

One category of such circuits utilizes-gaseous dischargetubes 'o-fthe thyratron type in amountingcircuitknowrr asthe Wynri Williamsf type and 1 described in Theory and Application of Electron Tubes by Reich, 2nd-edition, pages 486 and 487, published-bytheMcGraw-Jiill'Book Company. Impulse frequency dividing circuitsof this type are limited intheir speed 'of'operation due to tie-ionization time' and, therefore, are" restricted in'their use to the counting-of pulses which occurat a rather'low frequency per sec Another kind of frequency" dividing circuit-- utilizes grid controlled vacuum tubes in trigger circuits generally of the" Ec'cles Jordan type? Th'eprincipleof operation underlying the use of the trigger circuit-is that two electricalimpulses properly impressed on the circuit are required Therefore, a-connec-- to cycle the circuit once; tion to oneof'the-tubes-enables one pulse to be derived for every'two input-pulses impressed on the circuit. I

Counting circuits utilizing hard vacuum tubes" in circuits of the Eccles-Jorda-n "or flip-fiop type necessitate the use ofan electronic switch-"for commutating' observed input pulses alternately into the trigger tubes." The operation of-the elec-' tronic switch is preferably automatically syn-f chronized with the tubes in the trigger circuit 7 by means'of voltages'derived from the trigger circ'uit.-- Examples of such circuits are presented by'the patent te l /i chel,-No-. 2,343,016 and in the article entitled A Scale-of-IWdiiigh Speed Counter Using Hard Vacuum Tubes, by Lewis, Written in the-Proceedings'of the Cambridge Philoso'phical' Society, 1937; volume 33,'pages 549 to 5585'- It has been found that the circuits of the prior art, although-effective for the purposes for which they were designed, are 'deficientnpon appli cation to the'acourate counting of impulses occurring at a fast rate.

In accordance with the presentinvention, an

currenceof electrical impulses into a known -frac-' tional rate is accomplished by the combination of 1 known types of trigger circuits with a novel form iof commutation and interlocking system.

The trigger circuit of the-Eccles-Jordan type is capable of operatin at high speeds provided the time: constants of 'the 'cross coupling net'- works are keptsmall andgin addition, that means .beprovided-forlcommutating pulses into the circuit' without materially lengthening the time constants of the trigger circuit.

A further consideration arises due to the fact that the trigger circuit inherently provides a scaling factor of two. The attainment of scaling factors greater than two requires the coupling together of a plurality of trigger circuits in such manner as to operate in sequence. Such a combination of trigger circuits is capable of operating at high speeds provided the commutating of the input impulses in proper sequence into the respective trigger circuits is accomplished with networks havin short time constants, and connected in such manner as not to materially lengthen the response time of the trigger circuits. In addition to the above consideration, means must be provided for de-activating certain of the coupled trigger circuits in order to permit response of each circuit only in its proper turn. Here again, the de-activation circuit must have a' short time constant and must not lengthen the response time of the trigger circuits to which connected.

It is, therefore, an object of this invention to provide an impulse rate dividing circuit capable of responding to input pulses having a very high rate of occurrence.

Another object is the provision of a system for coupling a source of electrical impulses to a trigger circuit in such manner as to prevent impulse transmission back into the impulse source.

Still another object is the provision of interlocking coupling means between trigger stages in such manner as to enable operation of coupled trigger circuits in sequence,

Other and further objects and advantages will become apparent as the description proceeds.

The invention is described by reference to the accompanying drawing in which:

Figure 1 is an electrical circuit diagram illustrating in basic form the application of an improved electronic switch to a univibrator.

Figure 2 is a circuit diagram of two univibrators coupled in cascade by an extended application of the electronic switch shown in Figure 1.

Figure 3 is a series of charts showing pulse sequence in the circuit of Figure 2.

Figure l is a circuit diagram showing the combination of a pair of electronic switches for pro-perly cornmutating pulses from two sources into an Eccles-Jordan trigger circuit.

Figure 5 is a circuit diagram showing a single pole double throw electronic switch so connected to an Eccles-Jordan trigger circuit as to properly commutate a single source of pulses whereby results a scale-of-two circuit.

Figure 6 shows a scale-of-two circuit connected by means of the electronic switching circuit of the present invention to an Eccles-Jordan trigger circuit.

Figure 7 is a diagrammatic representation of several scale-of-two trigger circuits combined with an Eccles-Jordan trigger circuit to provide a division factor of five.

Figure 8 is a schematic representation of the commutation system of the present invention arranged for separating generating pulses into two channels.

Figure 9 is a circuit diagram of a ring scalcr circuit comprising hard vacuum tubes properly commutated by the improved switching means of this invention.

In the arrangement illustrated in Figure l, a univibrator is shown coupled to a source of electrical impulses by means of the improved commutating means of this invention. The univibrator is of a common type comprising tubes 20 and 22 having anodes and grids cross-connected in the usual manner. The input commutating network comprises a rectifier so connected to one of the univibrator anodes that it is biassed to a neutral condition until it delivers an input pulse and is then automatically biassed to non-conduction until the univibrator is again in a condition to be activated by a succeeding pulse.

In this embodiment, the rectifier is shown as a diode having a cathode 2 1 and an anode 25. It is understoodthat, although diodes of the vacuum tube variety are shown, the term diode is intended to include all types of rectifiers or uni-- directional conductors.

The cathode 24 of the diode is connected to the positive terminal marked B+ of a common source of anode potential. The anode of the diode is connected to the anode 26 of normallyofi tube 26 of the univibrator. It follows that the diode electrodes 24 and 25 are at equal potcntials whenever univibrator tube 20 is not conducting. It also follows that a conducting state of univibrator tube 20 causes a voltage drop in anode load resistor 38 so that the diode anode is at a lower potential than the cathode and therefore disconnects the univibrator from the source of electrical impulse.

Operation of the circuit thus described in response to impulses impressed on input terminals 36 is as follows: Tube 22 is initially conducting for the reason that its grid is not biassed negatively. The anode current of this tube causes a voltage drop in the anode resistor 32. The grid of tube 2i] is connected in a voltage divider netzork comprising resistors 32, 33 and 34. Resistor E l is so proportioned with respect to resistors 33 and 32 and bias potential source 49 that the grid of tube 20, during conduction of tube 22, is biassed below cut-off. The values of resistors 33 and 34 and the value of the bias potential source also are so proportioned that tube 29 is conductive when tube 22 is cut off due to the full available positive B+ potential eing applied across the resistors. Therefore, in the initial condition, tube 26 is non-conducting, tube 22 is conducting and anode 35 of tube 22 is negative relative to the value of the B+ potential. Anode 26 of tube 20 and both cathode 2 3 and anode 25 of the electron switch diode tube 23 are at the full B+ potential. There is, therefore, no appreciable potential difference between the diode electrodes. Upon the impression of a sharp, negative pulse on the input terminals 313, the potential of cathode 24 is depressed with respect to anode 25 thereby rendering diode 23 conducting. The negative pulse is therefore transferred to the anode 26 and through condenser 38 to the grid of tube 22. The negative pulse on the grid of tube 22 results in a positive pulse at its anode and therefore a positive pulse is impressed on the grid of tube 20. The positive pulse on the grid of tube Zil results in a negative pulse in its anode circuit which depresses further the grid potential of tube 22 and also cuts off electronic switch 23. The cycle of action thus described is self-perpetuating with the result that in a very short time, tube 22 becomes completely cut oil and tube 20 completely conducting.

Condenser 37 is provided to transfer the high frequency components of the voltage pulse generated at anode 35 to the grid of tube 20. Resistors 33 and 34 have a value so chosen that tube 25! remains conducting so long as tube 22 is nonegs-sa as 5. conducting. oenae ser 31 may 'be= of-siiiall value with the result that the ti'nie constant' of'the net "wc'rkcomprisingoehdenser 3'l' and resistor fl rnay be very short.

The set of conditions thusrar obtamed in the circuit is such that the anode 35'isat-the }ful1. B+ potential while anodes 26- an'd '25 are at low pot'eritial-due "to the IR 'dropacross resistor '38,

Upon the cessation of the negative going pulse applied-toinput terminals 30, the'cath'o'd'e 240i the diode tube regains'the run-"13+ potential {as seen as the "chargefonfcondenser 2-9 f=dissipates through resistor z8jwhereas. the ariode-ziismai-n- 'tained at less than B+- potentia1-bythe-anode current drop'throughresistor 38. it follows 'that the trigger tubes are effectively disconnected. fromth'e source ofinput'pulses for aslong as time 20'remains conducting. I

The trigger circuit in this embodiment-being {a univibrator, conduction is automatically "transferred back to initially conducting tube 22 due to the grid of tube '22 returning to the'catho'de potential as the charge on condenser '36 is dissipated through resistor 39. Tube 22-be'ginsa'g'ain 2 5 operations which very-quickly'restores 'full' cnduction to tube ZZ-a'nd-cutsoff 'tube20. Thecircuitis n'owba'ckin its original'stag'e.

It is important to note that during the time that tube is "conducting and after the very short interval taken by thelnetwork 28 and '29 to recover, the cathode 24 of the' switching diode is at the full B+potentia1 while theanode is at a valueless than run 13+ potentialwith*thef-re- Sult that no current can flew throughtl'ierectifi er 23 during the recovery process in the trigger stage and therefore, no iinpu1searising in the trigger stage can be reflected back to the 'input terminals 30. v I v Further, because the'commutating diode 23' becomes open-circuited immediately afterits-fu'nction is accomplished, thecir'cuit elements associat'ed'with the input circuit ar'e disconnected from those elements in the trigger circuit which determine-its speed of response.

A considerable advantage is derived from the fact'that the commutating' diode is coupled into the anode circuit of the trigger stage. Transients arising in the power supply eifect both electrodes of the diode equally, thereby-eliminating any susceptibility of the trigger circuit to re'spond to transients creating in this manner.

Another advantage derived from'the described mode of connection is that'even the capacitance of the switching diode :23 is -largelyisolated-from the control grids in'the trigger circuit. The reason for this is that'the impulse-generatediii-the anode circuit of tubeZU has asteep'terrriinati'on. The high frequency comp'onentsbf theimp'ulse are transferred to thegrid of't'ube 22throi1gh condenser 36 which therefore can be very small.

The diminutive capacitance of'con'de'nser 36, therefore, isolates to a considerable extent the capacitance of diode23 as well'as the circuit coinponen'ts'associated therewith. "It renews that'the "characteristics of the-diode or other type ofrectifier are not critical.

6 extension or the aboveprinciples {re eas caded trigger stages is e'xplained with-reference to Figures 2and-"3. By way of'eiiamplefa iinivib'rator stage similar to that discussed "withreference to Figure 1 -is* 'show'n coupled to asecond identical u'nivibrator. The components of the second 'un'ivibrator are similar to those'in the first 'uiiivibrator and are therefore Y indicated-by the same'reference numeralsin prim 'rm. 'I he seems uni'vibrator is coupled to' the ancaeef tube 22--by means of' the'swithing diode 23 v Up'o'n the' inipre'ssion of a'he'ga'ti pulse oh the fir 'st iiriivibrato'r stage, "the sequenceief events which followare-explainedwith- 'ref ere'rice' to Figure 3. Curve -A shows the negative pulse-impre'sse'd on input terr-riin'a'l's 30. Curve -B show's the resultant pulse impres'sed on cathode 2'4 of -the sWitching diode 23. Curve-Csh'o'ws the -re- 'sul'tarit positive pulse generated--at the anode of tube 22. The length of this positive pulse is de termin'ed by the product'of condenser- '35 and re- -"sistor 39. "-CurveD shows thedifferentiated pulse 'derived from "passing the positive pulse generated-fby' tube 22 through network'zil "and 28'. The "differentiated pulses are-impressedon cath- -'b ie 24' of s'w'itchingdiode 23'. The first differehti'ated 'pulse occurring at ti-ih'e-a-does not affect the second 'univibrator for the 5 reason that the switching diode 23 is open circuited to positive pulses. The second differentiated'pulse occurring attime b is negative and therefore is passe'd by switching diode 23 and is impressed on theanode ZB'of tube 20. This negative pulse-is transferred to the-gr-id'oftube 2'2 through'condenser 36" and "therefore'results 'in a positive pulseat the anode 35 as sh'ownin curve E. The-length of the positive pulse ap'pearin'gbn anode'-35,"thatis to say, the durationb--c in Figure 3,'is-fixed by the product of condenser 36 and resistor 39'. r

Fromthe foregoing; it is seen that although selected pulses derived from the first univibrator are injected into "the" second univibrator, no pulses created by the'a'ctibn of -the sk'a'c'zo'n'd univib'rator,

can be refle'cted back into the first 'univibrator.

The reason'fo'r this is the disconnect characteris- 'ftic ef the eommutating diode 23"dueto the mode bf'eonnection inci'reilit.

v --In'the applicatieh of trigger circuits td-the division of the frequency of occurrence of pulses to be counted-the trigger circuits of the flip-flop t'ype "rather than" the univibrator have particularly'-a'dvantageous characteristics. The reason *for thisis that'unlike the univibrator, the flip-flop circuit has two conditions of stabilityth'e'reby necessitating the application of two negative 'pulses to the tubes in order to complete one cycle ofthe' circuit.

aererring "to Figure 4, the novel electronic svvitch of'this inventionis shown applied to a ty ical *Eccles-J'ordan flip-flop circuit. 7 The circuit compr ses two'trio'detubes M ands! each-having ananc'de-loa'd resistor 43 and Ml respectively, and cross' coupling networks comprising resistor 45 and. condenser 4'6,and'resistor 4! and condenser 48; respectively. The 'valueof the circuit-componentsare so' chosen in the usual "manner that this circuit hastwo stable conditions. That is, if one'tiibe is conducting, the-grid of the other tube is held'below cut off. Coupledto'the respective anodes are'two commutating diodes'50 an d 5l and networks comprising condenser 52 and resistor =53, and-"condenserm and resistor 55, respectively. The operation or this circuit re iresthat electrical impulses be applied alter'nately'to the grids bf the' two tubes. Operation isas renews Starting with the assumption that tube H is the trigger circuit.

assaeoe conducting and an externally derived pulse is impressed on the right-hand input terminals 60, a negative component of the pulse is transferred to the grid of tube 4| through the switching diode 5!. The action of the negative pulse impressed on tube 4! results in the transfer of conduction to tube 42. As soon as conduction of tube 52 starts, the anode of switching diode 5! drops in value thereby disconnecting the first pulse source from Return of conduction to tube M is obtained by the impression of a negative pulse on input terminals 6i," and as soon as tube 4! becomes conductive, the second pulse'source is disconnected from the trigger circuit.

To the end that pulses derived from a single source will be impressed alternately on the tubes of a flip-flop circuit, the commutating diodes are arranged as shown in Figure 5. The resultant circuit, having a capacity to cycle once for every two input pulses, is known as a scaler or scale-ftwo circuit. Two triodes l8 and 7!, respectively, are shown connected similarly to those shown in Figure 4. Two commutating diodes, each having an anode and a cathode, have their anodes connected to the anodes of the trigger tubes in the same manner as that described with respect to Figure 4. The diode cathodes are connected together and through a resistance M are connected to the common source of anode potential. The cathodes thus joined are coupled to input terminals 15 through coupling condenser i5. Operation of the circuit is as follows:

It is assumed that tube F9 is initially conducting, causing the usual voltage drop in anode resistor ii. The value of the parts is such that the grid of tube a! is thereby biassed negatively to cut off. The cathodes of switching diodes i2 and 13 are at the full 18+ potential. The potential of the anode of diode i3 is the same as that of the cathode but the anode of diode i2 is depressed due to the potential drop created by the current of tube i9 through anode resistor H. The application of a negative pulse upon the input terminals therefore results in anegative pulse being commutated only through diode '53 to the anode of tube li. This negative pulse is transferred through cross-coupling condenser 8% to the grid of tube Iii. A slight reduction in anode current of tube '56 is caused, thereby creating a positive pulse on the anode 8! which is transferred to'the grid of tube it. The positive pulse on the grid of tube it causes a negative pulse on its anode 82 which is transferred to the grid of tube HI. The transfer is accumulative, tube "i0 is very quickly cut off, and tube ll becomes fully conducting. The circuit is now in readiness for a second inipressed pulse to reverse conditions and thereby complete the cycle. That is, the anode of commutating diode i2 is now at full 3-!- potential, a potential substantially equal to that ofits cathode. Therefore, the next negative impressed pulse will be transferred only through diode T2 to the anode circuit of tube it and thence through small condenser 8 1 to the grid of tube ll.

The rapidity with which the scaler circuit of Figure can respond to input pulses depends upon the time constants of the networks 8l85, and 8U83. This time constant is greatly shortened due to the fact that, except when transferring a pulse at the proper time into a responsive circuit, the commutating diode disconnects the input circuit. It follows that the only capacitances and resistances in the trigger circuit are those provided therein by the circuit elements and by the exercise of suitable precautions in lay-out and wiring, spurious capacitances can be minimized. In addition, tubes having low grid-to-cathode capacitance can be utilized to obtain extremely high operating speeds.

The basic expedient of this invention, which is the application of a properly biassed unidirectional conductor connected to anode circuits of trigger tubes, is applicable in the cascading of scaler circuits;

In addition, the second novel application of unidirectional conductors for the purpose of deactivating otherwise sensitive stages is now explained with reference to Figure 6.

A scale-of-two circuit is coupled to a flip-flop circuit in such a way that spurious responses due to feed-back are eliminated. The scale-of-two circuit comprises tubes 9% and 9| connected in the usual manner and provided with commutating diodes 94 and 95 connected in the manner of Figure 5. The flip-flop circuit includes tubes I00 and it! provided with commutating diodes I93 and 206 connected in the manner of Figure 4. An additional switching diode I05 is provided for a purpose presently to become apparent.

Operation of this circuit is now analyzed through a series of input pulses. Assuming an input pulse is impressed on input terminals I06 and that, initially, tubes 9! and iii! are conducting, the input pulse is passed by switching diode 9 3 to the grid of tube 9! due to the fact that the anode of non-conducting tube 96 is at full B+ potential. Since tubes 9| and I ill are conducting, the anodes of these tubes are at decreased potential and therefore, commutating diodes 95 and 984 are open-circuited thereby blocking the input pulse from the grids of tubes 921 and H30. The application of the negative pulse to the anode of tube 98 with resultant transfer to the grid of tube 9!, causes tube to become conducting and tube iii to become non-conducting.

The resulting full B+ potential on each electrode of diode renders it conducting to the second input negative pulse so that the second pulse is transferred to the grid of tube 90 thereby causing the scaler trigger stage to resume its original state. The regaining of a state of conductivity by tube-9i simultaneously create a voltage drop in anode resistor I08 thereby positively biassing diode I03. Accordingly, the negative pulse generated by tube 9i is transferred to the anode of tube Hi9 and from thence to the grid of tube lGi. As a result, tube NH cuts ed and during the process thereof, renders tube IEO conducting.

An explanation of the reaction of the circuit to the third input pulse serves to explain the use of the commutating diode for deactivating an otherwise ready input circuit 50 as to prevent operation of a trigger stage out of turn.

The scaler circuit comprising tubes 90 and 9| is in original condition with tube 9t non-conducting so that a third input pulse would normally be passed by diode 94 to the anode of tube 98 and from thence to the grid of tube St to cause it to respond. This action is prevented by the interlocking diode H15 which biasses to cut-01f input commutating diode 94 in response to the state of conductivity of flip-flop tube I053. The third input pulse, therefore, is effective only in re-setting the condition of flip-flop tubes I09 and I8! because tube HM, being non-conducting, no potential drop exists in its anode circuit and, therefore, commutating diode N14 is conducting. It follows that, in response .to the application of three input impulses on the input terminals I06 of the combined circuits, the flip-flop circuit, comprising etubes Ifilland It ,rhas undergoneone cycle of opv "erations and-one impulse-is generated on output terminal IIll. -Thereforegthe combination ofa :scale-of-twoicircuit and a flipefiop. circuit. proper- [1y "coupled by means of theswitchingidiodesof this inv'entiomresults in a-scale-of-three circuit. The novel arrangement including the commutating or switching diode is a "flexible expedient nnaking possible many 'other' desirable scaling tractors. "Forexample, Figure -7-diagrammatically shows two 'iscale-of-two -circuits connected in series -:and "followed :by-a :flipflop circuit. The 1 second. s'cale-oftwo fee'dsone side of the flip-flop circuit. The flip-flop circuit controls aninter- .rlo'ckingaswitching diode for the purpose of -dis- -abling' the first sealer except on the first four out :of each five input rpulsjes. --Pulses to be counted are'impressed'on thefirst scalerand'from thence to thesecon'd :scalerandthen tothe flip- 'fiop in the manner ofFigure 6. This arrangement provides a division "factor of-5. *The-addiction 'of another'scale of-two similarly connected *in' series w'ith the-first :two scale-of-jtwo circuits provides a scale-of-nine. It "follows that the :division factor r of this type :of' circuit is '-(2 1) "where n'tequals the-numberof scales-,of-two. :Fur- --ther,' the provision of a scale-'ofetwo circuit-preceding-or following the circuit of-yFigure-Tprovides "a'itotal scaling 'or dividing factor of 10. Y

*Itis seen, therefore, that any iscaling factor may :be obtained byxcombining commutating and --interlocking diodeswitha suitablerchoice ofscalmg and flip-flop :circuits. 7

By way io'f example, :thefollowing table is a guide r'to'thei selection :of basic :circu'its properly co'up'led'by commutating'dio'desto obtain a.-num- *ber ofsel'e'cted scaling f actors.

Scale of 3 -scale' oi": IZ-I-flip-Tlop .Scale of 4 -'scale of2. scale off2 'Scale -of 5=scale of '4 -|'-;flip-.fiop Scale of .6=sca'le' of 2 X scale of '3 1 Scale of 7=scale of '6+flip-.fi o p Lsca'lesof' 8= (scale of 2) 3 Scale of 9=scale of 3 x scale e Scale,of,10=scale of. 2 'scale of .5

fFurther'variations areavailable in the arrangement of the basic-:.circuits;for the accomplishment '.:of -:other desired-purposes. "For: example-Figure -8'shows an arrangement'whereby pulses derived from a 'singlesource may be swar-atedinaccord- -ance with a selected sequence into two channels. Input'pulse's are fimpressed on'the twochannels r-identified'=by the anumerals III) and'I I I. Each channel ieonsistsiofaiselected numberof cascaded scalers choseniin accordance with-the aboveitable. The. output of= the two channels-are coupled tothe tworsides' of a flipeflop circuitidentified generally by the numeral I I2. Theprovision-otaswitching diode teed-back arrangement for coupling'anode potentials "inthe *flip-fiop circuit back totheinput channels results in-al-ternately sw-itching-- a selected number of input-pulses fromone channel to the other. :Thus, if =cha-nnel -II I is initially sequential ipulses. The-iratio L of the :number ;of

machine operations. *provided at selectedpoints-within the channels so "that groups of pulses may be obtained having a :pulsesin" the two sets corresponds inversely to the scaling factor of thetwo respective channels.

This type of circuit'isuseful in computers and in Output terminals may be relation to the input pulses depending on the scaling factors'existing up to the selected-points.

'The applicationof the principles thus-far discussed areapplicable to a ringscaler circuit such as shown in- Figure 9.

Three-'fiip-fiop trigger circuits are provided and are coupled to each other by commutating diodes IZc and I25. The source of input pulses-is commutatedto the several trigger stages in-proper sequence by commutating diodes I23; I24 and I25.

The --initial ready condition of the circuit is that in which the left-hand tubein -the first stage and the right-hand tube in the remaining stages are conducting. This initial state is accomplished throughthe-provision of reset switchIZfi which is opened'for a short duration thereby enabling the imposition of a high positive potential on the grids of the left-hand tubein the=first stage and on the right-hand tube in the remaining stages. The initial condition having been obtained,

'switch I26 is'closed.

mutating diodes I'Zdand I25 are connected-tothe anodes of trigger tubes I33 and I35. These tubes are conducting with the result that thea'node potentials are depressed and therefore,the commutating diodes I24 and I25 are negatively biassed and open-circuited.

'The' first input impulse, therefore, is commutated by diode I23'to the-anode of tube I 3I and from thence tothe grid of tube I30. As a result, conduction is transferred from "tube I3II totube I'3I in the first stage.

Conduction by tube I 3| creates a negative pulse in anode load resistor IZI'thereby'depre'ssing the potential of the cathode 'of coupling' diode I20 "withthe' result that the pulse is transferredto the anode of'tube I32'and from thence to the grid of tube I33. 'This'action results'in'tubel32 becoming conductive and tube I33 becoming nonconductive. The result of tI1be'I33 becoming non conductive is the preparation "of commutating'diode I213 for passing the second input pulseto theanode oftube "I33 and'from thence tothe grid'of'tube I32. The second input pulse, therefore, renders tube I 33- conducting ithereby generatinga negative going pulse in anode" load resistor I28-which is .commutated through diode the grid of tube- I35. I35 becoming-non-con'ductive-andtube ltd conductive. The resultant increase in'potential of I2I to the anodeoftube I34 and from thence to Thisactionresults in tube the anodeof commutating diode I25 readiesit to transfer thethird. input pulseto tube I34 thereby causing the third'trigger stage to-flop back to-its original conduction. Therefore; the third input pulse causes tube 535 to again-become conductive, 'and'to' generate anegative pulse across anode load resistor I29. This negative pulse is commutated back to tube I38 throughcommutating diode I36 thereby re-setting the firststage for response'to the fourth inputpulse.

- It follows that-a ring :scaler; circuit-has a divi- --s ion factor-equal tothe-numberrof stages. Therefore, in the embodiment of Figure 9, three input pulses on input terminals I I9 result in one output pulse at output terminals Hill.

From the foregoing disclosure, it is seen that what has been described is a novel electronic switching circuit coupled in the anode circuits of scale-of-two and flip-flop circuits which makes possible greater speed of operation and greater reliability than obtainable in circuits avaliable in the prior art. Further, by the use of the diode switching circuits described, close matching of tubes and parts is unnecessary and deterioration of circuit components due to use does not affect the reliability of the device.

A further advantage of the novel combination of trigger circuits and commutating rectifiers of I the present invention lies in the unidirectional characteristic of the biassed diode which results in independence from input wave form provided a high negative rate of change is present in each cycle. Therefore, among other applications, the circuits of this invention are applicable to the measurement of any type of wave energy having a steep negative rate of change termination for each cycle.

The invent on has been described particularly with reference to triode tube vacuum tubes in tri ger circuits. However, any other type of grid controlled vacuum tube can be used.

Although the invention has been described with reference to certain specific embodiments, other modificat ons are possible. Therefore, the invention is intended to be restricted only by the ap pended claims as interpreted in view of the prior art.

What is claimed is:

1. In combination, a trigger c rcuit having a first and a second cross-coupled grid-controlled vacuum tube having at least one stable condition of cond ctivity and a common source of anode potential; means for triggering the circuit comprising a rect fier having a positive and negative terminal, means for connectin the positive terminal to the anode of the first of said vacuum tubes. and a resistance connecting the negative term nal to sa d common source of positive potent al. wh reby said rectifier is ne atively biassed when the first vacuum tube is conducting and is conductive under the impression of a negative pulse on the negative terminal when the first vacuum tube s not cond cting.

2. In combination, a trigger circuit having first and second cross-coupled grid-controlled vacuum tubes, an anode load resistance connecting each of the anodes of said tubes to a source of positive anode potential; and means for commutating negative input pulses only to the grid of the conducting tube comprising a rectifier havin a positive and negative terminal, means connecting the positive terminal to the anode of the first vacuum tube and impedance means connecting the negative rectifier terminal to a source of potential substantially equal in value to the source of anode potential, a source of negative pulses connected to said rectifier negative terminal having a peak value not exceeding the potential difference between the anode of the first vacuum tube when conducting and the anode potential source whereby said source of negative pulses are coupled to the grid of the second vacuum tube only when said first vacuum tube is in a condition 'of nonconduction.

3. In combination with a trigger circuit comprising a pair of thermionic tubes each havin a cathode, grid and anode, and having the. grids and anodes connected by cross-coupling networks in such manner that only one tube is capable of steady conduction at a time, said networks including a load resistance connected between a source of anode potential and each of the anodes; means for commutating triggering pulses into said trigger circuit comprising at least one rectifier having an anode and a cathode, means connectin the rectifier anode to a trigger tube anode whereby the potential on the rectifier anode is that of the trigger tube anode potential, a resistance connectin the rectifier cathode to a source of potential equal in value to the anodepotential source whereby the rectifier is negatively biassed to a condition of non conduction when said trigger tube anode is conducting current and is zero biassed substantially when said trigger tube anode is not conducting current,- means for impressin impulses having negative components on said rectifier cathode whereby said impulses trigger the trigger circuit when the said trigger tube anode is not conducting, and do not affect the trigger circuit when said trigger tube anode is conducting.

4. In combination with a trigger circuit having first and second thermionic tubes each having at least a cathode, control electrode and anode being cross-coupled by anode to grid networks, means for commutatin triggering impulses into said trigger circuit comprising a un directional conductor having a first and second terminal, means for connecting one terminal of the unidirectional conductor to the anode of the trigger circuit first tube, and a resistance connectin the second unidirectional conductor terminal to a source of positive potential having a value of potential equal to that of the first trigger tube anode under a condition of non-conduction, and means for impressing input pulses having a negative rate of charge on the said unidirectional conductor second terminal, whereby under the condition that the negative excursions of the input pulses do not exceed in peak value the potential of the positive potential source m nus the first trigger tube anode potential when conducting, said unidirectional conduction is able to impress triggering pulses on the trigger circu t only when said first trigger tube is non-conducting.

5. In combination with a univibrator having first and second grid-controlled tubes cross-c011 pled whereby the first tube is capable of a stable condition of conductivity, means for commutatil'lg negative pulses to the grid of the first tube comprising a rectifier having a cathode and anode, said rectifier anode being connected to the univibrator second tube anode whereby it is impressed with the full potential of an anode potential source when said second tube is not conducting, means connecting the cathode of the rectifier to said anode potential source whereby the rectifier is capable of conduction only during a condition of non-conductivity of the said second tube, and a source of pulses having a negative rate of change coupled to the rectifier cathode whereby said source of pulses is coupled to the grid of the conducting first tube to terminate the conduction thereof and render the second tube conducting thereby negatively biassing the rectifier and isolating the univibrator from the source of pulses until the original state of univibrator balance is restored in the usual manner.

6.'An impulse generating circuit adapted to generate impulses at half the rate of impulses impressed thereon comprising a trigger circuit and input impulse commutation means, said triggercircuitcomprising a pair of vacuumrtub'es each including at" least a cathode; grid: andanode, resistance networks=cross-connectecl between. theanodes andgrids wherebythe grid biasis: a function of the opposed anodepotential; resistancemeans connected'between each anodeand a source of anode potential; saidinput: impulse commutation means comprising a'pair of rec tifiers each having afirst and-second terminal and be ng adapted topass current under a conditioner a'potential onthe second terminalposi tive with respect to-the=potential"on the first-'ter mina-l', means conductivelyconnecting the second terminal of one rectifier to one trigger tube anode and means conductively connecting the second terminal of the other rectifier to the other trigger tube anode, means for impressing a positive potential on the first terminals of each of the rectifiers equal respectively to the potential of the anode of the tube to which it is connected under the condition of non-conduction of said tube, and means for impressing input impulses on the first terminals of the rectifiers.

7. In combination with a trigger circuit of the Eccles-Jordan type comprising a pair of grid controlled thermionic tubes; means for converting the same to a scale-of-two comprising a, pair of unidirect=onal conducting means each having a first and second terminal and being adapted to pass current only under the condition of the existence of potential on the second terminal positive with respect to the potential on the first terminal, means conduct vely connecting each of the second terminals to a respective one of the trigger tube anodes, means conductively connecting the first terminals together and to a source of impulses, a resistance connected to the first terminals, and means for impressing a positive potent-a1 on the free end of said resistance having a value equal to the potential of a trigger tube anode under the condition of nonconduction, whereby said unidirectional conducting means are adapted to commutate negative components of input impulses only to the grid of the conducting trigger tube.

8. An impulse generator comprising a scale-oftwo trigger circuit comprising a first and second grid controlled thermionic tube coupled to a flipflop c rcuit comprising a first and second grid controlled thermionic tube and adapted to generate one impulse for every three impulses successively impressed on the combined circuit, comprising a pair of rectifiers having the r anodes connected to the anodes of the scale-of-two trigger tubes, and having their cathodes connected together and to a source of input impulses and to a source of positive potential, means for commutating impulses generated bythe second tube of the scale-of-two trigger circuit to the first tube of the flip-flop circuit comprising a, rectifier having its anode connected to the anode of the first flip-flop tube and its cathode conductively connected with the anode of the second tube of the scale-of-two, means for commutating the third of each successive three input im pulses to the grid of the first tube of the fiip-iiop circuit comprising a rectifier having its anode connected to the anode of the flip-flop second tube and its cathode connected to the cathodes of the first mentioned pair of rectifiers; means for disabling the scale0ftwo trigger circuit from functioning under the infiuence of the third pulse comprisng a rectifier having its cathode connected in the anode circuit of the first flipflop tube and its anode connected to the first SCa1 e-0ftWOi;. tube: anode. and. output; terminals.

an. anode-and: having. the cathode connected to,

each second tube anode and. the. anode. connected to. each first. tube. anode; a. rectifier, having a cathode andan anode and being-connected between the second" tube. of: the last'triggercircuit and: the first-.tube of'thefirsttrigger circuit with the rectifier anode connected to the anode of the second tube of the last trigger circuit and the cathode connected to the anode of the first tube of the first trigger circuit; a plurality of rectifiers each having an anode and a cathode and having the anodes individually connected to the second tube anodes of each trigger circuit, means connecting the cathodes together to a source of positive potential, means for rendering the first tube of the first trigger stage and the second tube of the remaining trigger stages initially conducting, whereby each trigger circuit in response to an impulse impressed thereon activates the next successive trigger circuit for response to the next successive input impulse; terminal means connected to the last trigger circuit anode whereby a rate of l/n impulses per second are generated in response to n input impulses per second on n number of trigger circuits so connected.

10. An impulse rate dividing circuit comprising a plurality of trigger circuits each having a first and a second tube each having at least a cathode, grid and anode, a rectifier coupling successive trigger circuits each comprising a cathode and an anode and having the cathode connected to each second tube anode and the anode connected to each first tube anode; a plurality of rectifiers each having an anode and a cathode and having the anodes individually connected to the second tube anodes of each trigger circuit, means connecting the cathodes together to a source of positive potent al, means for rendering the first tube of the first trigger stage and the second tube of the remaining trigger stages initially conducting, whereby each trigger circuit in response to an impulse impressed thereon activates the next successive trigger circuit for response to the next successive input impulse.

11. In combination with a trigger circuit comprising at least one thermionic tube having an anode load circuit connected between the thermionic tube anode and a source of anode potential, a unidirectional current conducting device having an anode and a cathode, means connecting the anode to the thermionic tube anode, a resistance connecting the device cathode to a source of potential having a value equal to the potential of said thermionic tube source of anode potential, and a capacitor having one terminal connected to the device cathode whereby said device is adapted to impress impulses on said thermionic tube anode circuit under the influence of negative impulses impressed on the condenser free terminal only under a condition of current non-conduction 0f the thermionic tube.

12. In combination, a trigger circuit having at least one grid controlled vacuum tube including an anode, and means for triggering the circuit comprising a rectifier having a cathode and an anode, means for connecting the rectifier anode to the trigger tube anode, and resistance means for impressing a positive potential on the rectifier cathode having a value equal to the trigger tube anode under the non-conducting condition, whereby the rectifier is negatively biassed and open circuited when the trigger tube is conducting and is conductive under the impression of negative going potentials when the first vacuum tube is not conducting.

13. In combination with a trigger circuit comprising at least one thermionic tube having an anode load circuit connected between the thermionic tube anode and a source of anode poten- 15 tial, a unidirectional current conducting device having an anode and a cathode, means connecting the anode to the thermionic tube anode, a resistance connecting the device cathode to a source of potential having a value equal to the potential of said thermionic tube source of anode potential, and a terminal connected to the device cathode whereby said device is adapted to impress impulses on said thermionic tube anode circuit under the influence of negative impulses impressed on the terminal only under a condition of current non-conduction of the thermionic tube.

WILLIAM A. HIGINBOTHAM.

No references cited. 

